Process for the production of polyamide-6 from epsilon-caprolactam

摘要

The invention relates to a process for the production of polyamide-6 by polymerization of epsi-caprolactam with full re-use of extracted caprolactam and oligomers. The extract is not subjected to a pretreatment for reduction of the cyclic dimer content. By carrying out the polymerization in two steps, the first at an elevated pressure, but lower than the vapor pressure of the reaction mixture supplied, and the second at approximately atmospheric or reduced pressure, the cyclic dimer content of the polymerizate leaving the second polymerization step is kept at a constant level. The process offers a high degree of flexibility in terms of production capacity and composition and proportion of recycled lactam in the lactam feed for the polymerization.